From: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
Align the index to mapping_min_order in force_page_cache_ra(). This will
ensure that the folios allocated for readahead that are added to the
page cache are aligned to mapping_min_order.
Signed-off-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
---
mm/readahead.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/mm/readahead.c b/mm/readahead.c
index 2a9e9020b7cf..838dd9ca8dad 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -318,6 +318,8 @@ void force_page_cache_ra(struct readahead_control *ractl,
struct file_ra_state *ra = ractl->ra;
struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
unsigned long max_pages, index;
+ unsigned int folio_order = mapping_min_folio_order(mapping);
+ unsigned int nr_of_pages = (1 << folio_order);
if (unlikely(!mapping->a_ops->read_folio && !mapping->a_ops->readahead))
return;
@@ -327,6 +329,13 @@ void force_page_cache_ra(struct readahead_control *ractl,
* be up to the optimal hardware IO size
*/
index = readahead_index(ractl);
+ if (folio_order && (index & (nr_of_pages - 1))) {
+ unsigned long old_index = index;
+
+ index = round_down(index, nr_of_pages);
+ nr_to_read += (old_index - index);
+ }
+
max_pages = max_t(unsigned long, bdi->io_pages, ra->ra_pages);
nr_to_read = min_t(unsigned long, nr_to_read, max_pages);
while (nr_to_read) {
@@ -335,6 +344,7 @@ void force_page_cache_ra(struct readahead_control *ractl,
if (this_chunk > nr_to_read)
this_chunk = nr_to_read;
ractl->_index = index;
+ VM_BUG_ON(index & (nr_of_pages - 1));
do_page_cache_ra(ractl, this_chunk, 0);
index += this_chunk;
--
2.40.1
